title: Do intermolecular association phenomena occur in B. cereus beta-lactamase I?
abstract: Although at fixed enzyme concentration the hydrolysis of cephaloridine by B. cereus beta-lactamase I followed apparently classical Michaelis-Menten steady-state kinetics, the values of kcat and of Km depended linearly, in the absence of added non-enzymatic proteins, on the absolute enzyme concentration. In the presence of gelatin, this dependence was abolished; under these conditions, however, the pseudo-first order kinetic rate constants of inactivation by Zn2+ ions exhibited a direct dependence on enzyme concentration and an inverse one on Zn2+ ions concentration. These results can be interpreted as indicating that intermolecular association phenomena play a role in determining the catalytic properties of the enzyme.
mesh_terms: D001409:Bacillus cereus / Q000201:enzymology*; D005780:Gelatin / Q000494:pharmacology; D046911:Macromolecular Substances; D010405:Penicillinase / Q000378:metabolism*; D013997:Time Factors; D015032:Zinc / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D005780:Gelatin; D010405:Penicillinase; D001618:beta-Lactamases; D015032:Zinc